This is a request for partial support for the meeting and for production of Technical Proceedings of this International Symposium. It has been five years since the last in-depth American College of Nuclear Physicians and Society of Nuclear Medicine Symposium on the subject of single photon emission computed tomography (SPECT). At that time, SPECT was just emerging as a clinical modality, commercial instrumentation was in the developmental stages, routine clinical applications were limited to one or two organ systems, and diagnostic experiences were limited to mainly academic centers. SPECT offers the practical utility of providing improved imaging contrast at depth in tissue - important advantages for tumor, cardiac and brain imaging. The objectives of this Symposium are to survey the progress of SPECT clinical applications that have taken place over the last five years and to provide practical and timely guidelines to users of SPECT so that this useful clinical imaging modality can be fully integrated into the evaluation of pathologic processes. Today, rotating gamma cameras capable of SPECT imaging are available from many commercial suppliers and this tomographic technique is becoming integrated into the array of diagnostic imaging tests. However, SPECT has not yet achieved routine utilization imaging, rather difficulties with SPECT utilization seem to center about two major areas: (1) Radiology and Nuclear Medicine Departments contemplating the purchase of SPECT equipment are unsure of how to best apply this technology to their patient populations and (2) SPECT equipment which is already purchased is being utilized primarily for planar gamma camera imaging because of the critical demand for quality control needed to generate clinically acceptable studies. The topic of SPECT imaging has been selected for this Symposium based on the results of annual surveys conducted at the 1984 and 1985 Annual Meeting of the Society of Nuclear Medicine where SPECT imaging was nominated as the single most desired symposia topic.